A groundbreaking fossil discovery in Ethiopia has the potential to rewrite the human family tree, challenging the iconic Lucy's place as our direct ancestor. This mysterious find, known as the Burtele foot, has been linked to a lesser-known human relative, Australopithecus deyiremeda, which coexisted with Lucy's species, Australopithecus afarensis. Published in Nature, the research reveals a more complex picture of early human evolution, suggesting that multiple hominin species adapted to upright walking in different ways.
The Burtele foot, consisting of eight bones and dating back 3.4 million years, showcases a unique feature: an opposable big toe. This indicates a species adept at tree climbing, unlike Lucy's species, which was adapted for upright walking. Yohannes Haile-Selassie and his team suspected early on that the fossil didn't belong to A. afarensis, and subsequent discoveries, including a partial jaw and teeth assigned to A. deyiremeda, confirmed their suspicions.
Haile-Selassie explains that this discovery highlights the diverse forms of bipedalism among early human ancestors, suggesting a more nuanced evolution than previously thought. Furthermore, isotope analysis of A. deyiremeda's teeth reveals a diet primarily consisting of trees and shrubs, contrasting with Lucy's species, which had a more varied plant-based diet. This dietary difference, along with distinct locomotive adaptations, allowed both species to coexist without direct competition.
The implications of this discovery are significant. It suggests a bushier, less linear human family tree, with multiple species evolving alongside each other. Fred Spoor from the Natural History Museum in London points out that A. deyiremeda shares traits with older and more recent fossil species, indicating a complex web of human relatives.
However, the question of which species led to modern humans remains unanswered. While A. anamensis is suggested as a potential ancestor, Ryan McRae from the Smithsonian cautions that more fossil evidence is needed to confirm any direct lineage. This discovery opens up a fascinating debate and invites further exploration into the intricate story of human evolution.
